<template>
  <div>
    <router-link v-show="showAbs" tag="div" to="/" class="header-abs">
      <span class="iconfont header-abs-back">&#xe624;</span>
    </router-link>
    <div :style="opacityStyle" class="header-fixed" v-show="!showAbs">
      景点详情
      <router-link to="/">
        <div class="iconfont back-icon header-back">&#xe624;</div>
      </router-link>
    </div>
  </div>
</template>
<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  mounted () {
    window.addEventListener('scroll', this.handleScroll)
  },
  beforeDestroy () {
    window.removeEventListener('scroll', this.handleScroll)
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {
          opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  }
}
</script>
<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    z-index: 1
    position: absolute
    left: .2rem
    top: .2rem
    width: .7rem
    height: .7rem
    border-radius: .4rem
    background: rgba(0,0,0,.7)
    text-align:center
    line-height:.7rem
    .header-abs-back
      color: #fff
      font-size: .4rem
  .header-fixed
    z-index: 1
    position: fixed
    top: 0
    left: 0
    right: 0
    height: .86rem
    line-height: .86rem
    text-align: center
    color: #ffffff
    background: $bgColor
    font-size:.35rem
    .header-back
      width: .64rem
      text-align:center
      font-size: .4rem
      position: absolute
      top: 0
      left 0
      color: #ffffff
</style>
